Genetics

Question 1

Genetics

Answer 1

The study of the inheritance of characteristics

Question 2

Inheritable characteristics

Answer 2

Many physical characteristics such as eye colour and of ears were inherited from your parents

The instructions for these inherited characteristics were carried in the two cells that made you the egg and sperm

Question 3

Examples of inherited Characteristics

Answer 3

The way you fold your arms,ear lobes,pinky fingers,thumbs,widows peak and the way you can fold your tongue

Question 4

Chromosomes and genes

Answer 4

The nucleus of each sex cell(gamete)contains 23 thread like structures Chromosomes are made of protein + DNA
• These chromosomes carry genes
• Genes are chemicals found on chromosomes that pass on information from parents to children
• Deoxyribonucleic acid

Question 5

Egg and sperm

Answer 5

When an egg and sperm cell fuse (each has 23 chromosomes) they give the individual they are creating 46 chromosomes
• One set comes from the mother the other from the father

Each characteristic will be controlled by a pair of genes
• If the gene from the sperm is brown eyes and the gene from the egg is brown eyes then the child will have brown eyes
• The child is said to be homozygous for brown eyes, as she has only one type of eye colour gene

Question 6

Eye colour

Answer 6

Each characteristic will be controlled by a pair of genes
• If the gene from the sperm is brown eyes and the gene from the egg is brown eyes then the child will have brown eyes
• The child is said to be homozygous for brown eyes, as she has only one type of eye colour gene

• If the gene from the sperm is for blue eyes and the gene from the egg is for blue eyes then the child will have blue eyes. The child is homozygous for blue eyes.

• If the gene from the sperm is for blue eyes and the gene from the egg is for brown eyes one of the genes is usually stronger and this one is the one that will be seen in the child
• This stronger gene is called the dominant gene
• The weaker gene is called recessive
• Brown eyes are dominant over blue eyes
• The child will be heterozygous brown eyed.
• A big letter is used to show the dominant gene while a small letter is used to show a recessive gene
• If b represents eye colour then B is for brown eyes and b is for blue eyes
• These letters are used in genetic crosses, to see the likelihood of a gene being passed on to the next generation

Question 7

Example

Answer 7

A sperm meets an egg
• The sperm has the gene B for brown hair • The egg has the gene b for blonde hair
• What colour hair will the child have?
Bb Bb = genotype of the baby
Heterozygous brown hair = phenotype

Question 8

Dominant gene

Answer 8

The is the one that appears in the child when two different genes are controlling a characteristic

Question 9

recessive gene

Answer 9

The does not appear in the child when two different genes are controlling a characteristic